Decreased Heart Rate Variability as a Marker of Post-Traumatic Stress Disorder after Traumatic Brain Injury

Background and/or Objectives: The sympathetic nervous system is a branch of the autonomic nervous system that largely contributes to the stress response. Decreased heart rate variability (HRV), a measurement of increased sympathetic activity, is associated with post-traumatic stress disorder (PTSD). Treatment modalities aimed at increasing HRV have been shown to improve symptoms of PTSD. However, our search found no published reviews on the relationship between HRV and PTSD in patients with traumatic brain injury (TBI), despite up to 36% of people with TBI being diagnosed with PTSD. Our objective is to review recent literature on the association between HRV and PTSD after TBI.

Design: Narrative Review

Setting : Electronic Database

Participants : PubMed electronic database was searched on March 5, 2025. Searches were open to all languages. All resulting studies were assessed by one reviewer for original research with HRV and PTSD exclusive to patients with TBI.

Interventions: N/A

Main Outcome Measures: Qualitative analysis of each manuscript’s methodology, sample size, type of brain injury, and significant and non-significant findings were extracted and compared.

Results: Only two original studies analyzed HRV in individuals with TBI and PTSD. A cross-sectional analysis found that among 28 combat veterans, decreased HRV was significantly associated with having a combination of pain, PTSD, and mild TBI. A randomized controlled trial of 22 veterans with PTSD and mild TBI demonstrated that participants had more parasympathetically mediated HRV after transcutaneous vagus nerve stimulation. Other studies found traits associated with PTSD, including anger, anxiety, and irritability were associated with sympathetically mediated HRV in mild TBI.

Conclusions: Our review found that PTSD and symptoms related to PTSD are associated with decreased HRV and elevated sympathetic activity in people with mild TBI. Further research establishing this relationship can possibly lead to improved treatment of PTSD for people with brain injury.